Introducing GNSS Navigation Message Authentication
September 25, 2024 17 minute read
Please note that OSNMA functionality is currently available only in the next branch of the upstream repository and will be included in the next stable release of GNSS-SDR.
GNSS signal spoofing has become a frequent and concerning issue, particularly in regions experiencing military conflicts. This phenomenon can be monitored through various online platforms that use ADS-B data to detect and display, in near-real time, instances of aircraft being jammed or spoofed worldwide. In such scenarios, GNSS signal authentication is crucial for mitigating the effects of spoofing. This can be achieved by detecting spoofed signals at various stages of the signal processing chain, depending on the service provided by the system operator and the user’s receiver. If spoofed signals are detected, the receiver can respond by either issuing appropriate warnings to the user or excluding non-authenticated satellite signals from the computation of Position, Velocity, and Time (PVT) solutions.
Galileo, the European GNSS, is currently testing its Open Service Navigation Message Authentication (OSNMA) service. OSNMA is designed to provide a secure, spoof-proof communication channel between satellites and receivers. This service transmits authentication data within the Galileo E1 I/NAV messages, alongside the navigation data used by receivers to compute PVT solutions. By incorporating OSNMA, the resilience of GNSS receivers to spoofing attacks is significantly enhanced, since they can detect spoofed signals and act upon that event.
